#include <bits/stdc++.h>

#define FOR(i, a, b) for (ll i = (a); i < (b); i++)
#define RFOR(i, a, b) for (ll i = (b)-1; i >= (a); i--)
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define rep1(i, n) for (ll i = 1; i <= (n); i++)
#define rrep(i, n) for (ll i = (n)-1; i >= 0; i--)

#define pb push_back
#define mp make_pair
#define fst first
#define snd second
#define show(x) cout << #x << " = " << x << endl
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define pii pair<int, int>
#define vi vector<int>

using namespace std;
template <class S, class T>
ostream& operator<<(ostream& o, const pair<S, T>& p)
{
    return o << "(" << p.first << "," << p.second << ")";
}
template <class T>
ostream& operator<<(ostream& o, const vector<T>& vc)
{
    o << "sz = " << vc.size() << endl
      << "[";
    for (const T& v : vc)
        o << v << ",";
    o << "]";
    return o;
}
using ll = long long;
constexpr ll MOD = 1000000007;

constexpr ll MAX = 5000000;
bool isprime[MAX + 1];
vector<vector<ll>> digits;
vector<ll> prime;
bool allowed[10];

bool toomuch(ll head, ll tail)
{
    rep(i, 10)
    {
        if (not allowed[i]) {
            if (digits[tail][i] - digits[head - 1][i] > 0) {
                return true;
            }
        }
    }
    return false;
}

bool shortage(ll head, ll tail)
{
    rep(i, 10)
    {
        if (allowed[i]) {
            if (digits[tail][i] - digits[head - 1][i] <= 0) {
                return true;
            }
        }
    }
    return false;
}

int main()
{
    for (ll i = 2; i <= MAX; i++) {
        isprime[i] = true;
    }

    for (ll i = 2; i <= MAX; i++) {
        if (isprime[i]) {
            for (ll j = 2; i * j <= MAX; j++) {
                isprime[i * j] = false;
            }
        }
    }

    int n;
    cin >> n;
    rep(i, n)
    {
        int a;
        cin >> a;
        allowed[a] = true;
    }


    digits.resize(1);
    digits[0].resize(10);
    rep(i, 10)
    {
        digits[0][i] = 0;
    }
    prime.pb(0);
    for (ll i = 2; i <= MAX; i++) {
        if (isprime[i]) {
            prime.pb(i);
        }
    }
    const ll pnum = prime.size();
    for (ll i = 1; i < pnum; i++) {
        digits.pb(vector<ll>(10));
        bool digit[10];
        rep(j, 10)
        {
            digit[j] = 0;
        }

        ll p = prime[i];
        while (p > 0) {
            digit[p % 10] = true;
            p /= 10;
        }
        rep(j, 10)
        {
            if (digit[j]) {
                digits[i][j] = digits[i - 1][j] + 1;
            } else {
                digits[i][j] = digits[i - 1][j];
            }
        }
    }

    ll maxint = numeric_limits<ll>::min();
    ll head = 1;
    ll tail = head;
    while (tail < pnum) {
        if (tail < head) {
            tail++;
            continue;
        }
        if (toomuch(head, tail)) {
            head++;
            continue;
        }
        if (not shortage(head, tail)) {
            maxint = max(maxint, prime[tail + 1] - prime[head - 1] - 2);
            if (tail == pnum - 1) {
                maxint = max(maxint, MAX - prime[head - 1] - 1);
            }
        }
        tail++;
    }

    if (maxint == numeric_limits<ll>::min()) {
        cout << -1 << endl;
    } else {
        cout << maxint << endl;
    }

    return 0;
}